Centralized traffic control system



Sept. 6, 1938. V o. H. DICKE 2,129,168

CENTRALIZED TRAFFIC CONTROL SYSTEM Filed May 24, i930 4 Sheets-Sheet l INVENTOR avg (Mg Sept. 6, 1938. o. H. DICKE 2,129,168"

I CENTRALIZED TRAFFIC CONTROLSYSTEM Filed May 24, 1930 v 4 Sheets-She et 2 [Common c sum/ 52 I V INVENTOR JL ATTORN EY Sept. 6, 1938. o. H. DICKE 2,129,168

CENTRALIZED TRAFFIC CONTROL SYSTEM Filed May 24, 1930 4 Sheets-Sheet 5 Sept. 6, 1938. o. H. DICKE GENTRALIZED TRAFFIC CONTROL SYSTEM 4 Sheets-Sheet 4 Filed May 24, 1950 INVENT R 0 Lozmuum Patented Sept. 6, 1938 2,129,168 CENTRALIZED TRAFFIC CONTROL SYSTEM Oscar H. Dicke, Rochester, N. Y., assignor to Ge eral Railway Signal Company,

Application May 24,

38 Claims.

This invention relates to centralized traflic controlling systems, and particularly to a system in which a large number of distant traflic control devices located at various points may be controlled from, and a large number of indications transmitted to, a local central ofiice over a comparatively few line wires.

In accordance with the present invention, it is proposed to employ two circuits extending along a railway track, comprising three line wires, one wire of which is common to the two circuits mentioned. It is further proposed to select any one of a large number of way stations independently by a distinctive code, and to provide means for controlling several distinctive devices at each of said way stations when such way station has been selected and to receive indications from such way station.

The system under consideration is a system that is normally at rest, and in order to indicate in a local office the occurrence of a certain event at a distant way station immediately after such occurrence, it requires the ability for a particular way station to communicate with the local or cen tral office. Since theway stations are selected by a code, it would at first hand appear that suitable lock-out means would be required to prevent two way stations transmitting codes to the local ofiice in over-lap relation, thereby resulting in a jumbled up code. This, however, is not the case in accordance with the present invention, this because the central ofiice is the code radiating point for selecting a distant way station by a distinctive code transmitted over, what is conveniently called a stepping circuit or coding circuit, and the other circuit, conveniently called the message circuit, is employed to enable a way station to dictate the code, so to speak, which is to be transmitted from the central office to communicate with a particular way station.

It would then, on first thought appear that if two way stations were dictating what code shall be transmitted from the central ofiice at the same time, there might be conflict between these dictations of code, but this is not the case, in that the dictation of a code is obtained by short circuiting the message circuit and in not short circuiting the message circuit at a particular instant, and if the message circuit is shorted at one point, it is immaterial whether or not it is shorted at another point. The short circuiting of the message circuit is a dominating effect, so that if two or more way stations are endeavoring to dietate a code which is to radiate from the central oflice over the stepping circuit, the particular Rochester,

1930, Serial No. 455,349

way station, of

the way stations endeavoring to communicate with the central office, whose code has the largest prior order will be dominating code.

number of dominating steps in selected because it has the Putting this in different language, for in-coming messages the polarity code impressed on the stepping line is determined by whether or not the message circuit was preceding step, and short circuited short circuited on the next if the message circuit was on the next preceding step a positive impulse is transmitted over the stepping circuit, and if the message circuit was not short circuited on the preceding step a negative impulse is transmitted over out-going messages central oifica From the stepping circuit, and for the codes originate in the this it is apparent that positive impulses follow superior or dominating steps,

and negative impulses follow inferior steps, in

that positive impulses are obtained by short circuiting the message circuit, and that the short circuiting of the message circuit by one way station cannot be disturbed by a conflicting code at another way station short circuiting.

which does not require such From these considerations, it is apparent that any one of a large number of way stations may get into communication with a central ofiice independently through of a particular code,

a lock-out, it however,

the medium of the dictation and without the provision of being understood that a slow acting relay is used at each Way station for manifesting that the system is in operation or is not in operation, this slow acting relay, however, not being a lock-out relay in that it produces the same effect at the central ofilce and at each way station. These slow acting relays (I, I I may cycle demarking relays, their operation the limits of the various cycles.

In accordance with the central oflice ha the present invention, if

s been connected to a particular way station through the medium of a distinctive code, either oifice equipment or determined by the central dictated over the message circuit by such particular way stations equipment,

the succeeding steps up distinctive ticular apparatus at to the central office As heretofore lar code for an in polarity of each of over the stepping circuit set message circuits connecting parthat particular way station equipment. explained, the steps of a particu- -coming message, and the its steps determined in accordance with whether or not the message circuit was short circuited during the next precedinformation of interest to the ticket agents, crossing watchman, and the like, along the railway system.

Other objects, purposes and characteristic features of the present invention will in part be apparent from the accompanying drawings and will in part be more specifically pointed out hereinafter.

In describing the invention indetail, reference will be made to the accompanying drawings in tem illustrated;

Fig. 2 illustrates the way station apparatus for the west end of a passing siding PS; and

Fig. 3 illustrates a modified form of way station apparatus, eliminating certain half-step relays, and used for controlling the apparatus at the east end of the passing siding PS.

Structure Referring to Figs. 1A and 1B of the drawings, the top portion of Fig. 1B illustrates a series of code responsive stepping relays, I, IA, 2, 2A, 3, 3A, 4, 4A, 5, 5A, 6,

series of stepping relays H, HA, l2, I2A, I3, I3A, l4, MA, l5, I5A, I6, I! and I8 respond only to a code of minus, minus, plus, plus, minus, plus, minus and plus. more particularly to Fig. 1A

lamps IW and IE being controlled by the indicating relays IR and IE respectively. With the west end of the miniature passing siding 12s are associated the signal lever SL and the switch machine lever SML whereas the east end of the miniature passing siding ps has associated therewith a signal lever SL and a switch machine lever SML these levers controlling the apparatus at the passing siding PS through the medium of the selector system embodying the present invention.

As heretofore mentioned, the code current impressed on the stepping circuit including the line relays LR, LR and LR has its code at times determined by the central ofiice equipment and is at times dictated by one or more way stations in accordance with whether or not the message circuit has been short circuited. In accordance with the present invention, this code originates at the code relay COR and is dictated by the way station equipment when the transfer relay TRS is deenergized, but originates from the central oflice equipment when the transfer relay TRS is energized, and the code is then repeated to the code repeater relay CRR, which through the medium of main relays MR and MR applies impulses to the stepping line in polarity code fashion and in accordance with the condition of energization of the relay COR. In order to provide a definite demarkation between successive impulses of like sponse to the energization of the starting relay CR, and

selecting relay SFR, which is also interlocked with the lever selecting relays SLR SLR and SLR is employed to prevent the incoming signals from way stations interfering with theout-going signals or controls transmitted in accordance with lever positions. These lever interlocking relays SLR SLR and SLR may, however, be omit- These interlocked selecting relays SLR SLR SLR and SFR are controlled by the lever relays RL RL RL and the field relay FR, respectively. In the the selecting lever relays SLR SLR SLR, etc., are emitted, a push button will be provided relays I IA 2 2A 3 3A 4 4A 5 5A 6 I and 8 which relays are controlled in response to operation of the line relay LR and the operation of the slow acting or cycle demarking relay I providing that the line relay LR operates to transtop part of Fig. 1B of the drawings, which code is minus, minus, plus, minus, minus, plus, minus, plus, as indicated by corresponding signs within these stepping relays. Similarly, referring to Fig. 3, the code responsive stepping relays I I I2 I3 I4 I5 I6 11 and I8 are controlled by the line relay LR ,the slow acting relay I and the half step relay group comprising the even relay E, the odd relay 0, and the polar relay P, providing, of course, that the line relay LE is stepped in code of like fashion to constitute the code to which this particular series of code stepping relays will respond, which is a code of minus, minus, plus, plus, minus, plus, minus, plus.

The announcer relays Al-t and AR shown in Figs. 2 and 3, respectively, are energized only if the first impulse of a cycle, which impulse is pref erably of long duration and continues until the announcement has been completed, transmitted over the stepping circuit is of positive polarity.

In Figs. 2 and 3 have been shown respectively the relays DB SR SW and DB SR SW which relays are conveniently called control relays, and .are used to control respectively the signals and switch machines at the west and east end of the passing siding PS, all in a manner as described in the patent of S. N. Wight, Patent No. 1,889,457, dated November 29, 1932, as conventionally illustrated by the dotted lines.

Referring now to the passing siding PS shown in part in Fig. 2 and in part in Fig. 3 of the drawings, this passing siding PS is used as a meeting point for trains moving in opposite directions, and to enable one train to pass another from the rear, if desired. In practice many such passing sidings are used in a single system. The main track and passing siding have been illustrated by rails 30, which rails are divided by insulating joints 3! to constitute the usual detector track circuit, the one at the west end of which is provided with a track battery 32 and a track relay TR and the detector track circuit at the east end of which includes a track battery 33 and a track relay TR The track switch at the west end of the passing siding PS is controlled by the switch machine SM and the track switch at the east end of the passing siding PS is controlled by the switch machine SM In accordance with the usual practice in single track signalling, the west end of the passing siding PS is provided with a main entering signal 35, a take-siding signal 36, a main starting signal 31, and a dwarf starting signal 38, and similarly the east end of the passing siding PS is provided with a main entering signal 40, a take-siding signal 4!, a main starting signal 42 and a dwarf starting signal 43.

In order to initiate the system to transmit an indication from the way station to the central oflice upon a change in the position of the track relays TR and TR or other traffic controlling devices, the change relays M and M are provided, which in turn control the repeater change stick relays FR and FR Having now specifically referred to each of the elements of the conventional illustration of the systems embodying the present invention, it is deemed expedient to consider the operation of the system in detail, this in order to more clearly understand how the various elements of the system are interconnected, as well as the functions which may be carried out by the system, the extent to which. the system may be expanded without the embodiment of a prohibitive number of impulses per unit code, and the speed at which controls may be transmitted to and indications received from a large number of separated way stations.

Operation Table of codes.-Before the specific operation of the system is taken up, it is considered helpful to give a table of all the codes that may be used, in the order of their superiority. In this connection, it should be understood that the first five relays in each series constitute in reality the code responsive portion of the series, the last three relays responding to alternate plus and minus impulses carrying out particular functions at a particular way station. With this understanding of the system, the codes are given in the order of their superiority, which means that of any selected group of codes which want to come in at the same time, the code which stands highest in the table dominates the other codes which are endeavoring to dictate the code by which the central ofilce shall call them. These codes in the order of their superiority are as follows:---

As already stated, the first step in each code is negative, this to enable a way station to dictate to the central ofiice what polarity the second step shall be, as is clearly apparent from the table.

C'ode determination for oat-going station selection As already mention-ed in a general way, station selection in the present system is determined by codes of impulses transmitted over the stepping circuit, these codes comprising various patterns or combinations of positive and negative impulses.

These impulses originate in the central office but are determined in several different ways. Upon initiation of the system in response to the movement of a lever in the central ofiice, these" impulses are determined by contacts on a series of relays directly associated with that lever, but if the system is initiated because one or more way station change relays, such as relay FR?) are energized, the impulses are dictated by the relays at such one or more Way stations.

Referring particularly to the oifice equipment shown in Figs. 1A and 1B and the way station equipment shown in Fig. 2, let us assume that the operator in the central office wishes to allow an east bound train to pass into the sidetrack oi the passing siding PS, and in order to do so moves the signal lever SL toward the right, signifying east bound trafiic and moves the switch machine contact 41 of the relay RL wire 48, winding of the relay RL to the terminal of the same battery.

With the relay RL picked up the closure of its front contact 50 will pick up the selected lever relay SLR through the following pick-up circuitz beginning at the terminal front contact 5B of the relay RL wire 5!, winding of! the relay SLR wire 52, back contact 53 of the relay SLR wire 54, back contact 55 of the relay SLR wire 55, back contact 51 of the relay SFR, tothe terminal With the relay SLR once picked up it is stuck up through the following stick circuit:beginning at the terminal back contact 58 of the relay 8, wire 59, back contact 60 of the relay l8, wires BI and 69, :front stick contact 62 of the relay ZSLR wire 63, winding of the relay SLR wire 52, back contact 53. of the relay SLR wire 54, back contact 55 of the relay SLR, wire 56, back contact 57 of. the relay SFR to the terminal of the same battery.

In studying the pick up and stick circuits for the various relays SLR SLR etc., it will be noted that they are so interlocked that if any one of these relays has been picked up no other relay of this same group can be picked up. Also, it will be noted that the circuits for these relays priority in the order from left to right, this because if two of the relays such as RL and RL are picked up at the same time, the relay RL will have a dominating effect, in that with its contact 50 raised no energy can be supplied to the relay SLR whereas energy can be applied to the relay SLR. so long as no other relay to the right thereof, such as SLR or SLR has already been stuck up.

With the relay SLR, now energized through its stick circuit, its front contact 65 is closed, thereby completing the following circuit for the starting relay -CR:beginning at the terminal of the central ofiice battery, back contact 66 of the slow acting relay I (see Fig. 13), wire 61, winding of the starting relay CR, Wire 68, front contact 65 of the relay SLR, to the terminal of the same battery.

With the starting relay-CR energized, the following pick-up circuit is closed for the control relay W:-beginning at the terminal front same battery.

With the relay W once picked up it is stuck up through the following circuit:-beginning at the terminal of the central oilice battery, back contact 58 of the relay 8 (see Fig. 1B), wire 55, back contact 60 of the relay l8, wires GI and [3, stick contact 74 of the relay W, wire 12, winding of the relay W to the terminal of the same battery.

With the control relay W energized its front contact :5 is closed, thereby closing the following energizing circuit for the master relay MR beginning at the terminal front contact of the relay W, wire 76, back contact 11 of the channel time relay CT, wire 18, contact 19 of the position, Wire 80, Winding of the master relay MR wire n8l, back contact 82 of the master relay MR to the terminal of the same battery. y I

Picking up of the master relay MR effects closure of its front contact 83 included in the CT, because this circuit is open .at the front contact 66 of the relay I (see Fig. 1B).

Picking up of the contact 84 of this relay MR however, app ies current of negative polarity to front cont-act 84 of the master relay MR wire 81, front contact 88 of the control relay W, wire 89, 1 contact 90 of the push button PB, step-ping wire the terminals (3+) and LE etc., to. be moved to their left hand position.

' 9.5 of the relay LR, wire 96,

ticn No. 2 (see Fig. 2) movement of the contact LR to its left hand posiing relay I wire I55 and H16, winding of the to the movement of the line relay LR to its left relay requires negative poreason the action of the relays Il-l8 will not for reasons just explained,

() of the 80 and m, back contact :12 of the relay IA wire H3, front stick contact -I M. of the relay I, wires 99, I05 and IOI to the After a very short interval of time, but a longer interval of time than is required for the code responsive stepping relays I and I to pick up, the slow acting relays I and I are picked up, through circuits including respectively the contacts I25 and I26 of the relays LR and LR which circuits are readily traced in the drawings. Picking up of the relays I and I breaks the pick-up circuit for the relays I and I but since these relays are energized through stick circuits heretofore' traced, they remain in their energized position. Picking up of the relays I and I also effects breaking of the starting circuit and renders the message circuit available for use, by shifting of the contacts I28 and I29 of these respective relays, the function of which contacts I28 and I28 will be more particularly described hereinafter. Further, picking up of the relay I closes the following stick circuit for the transfer relay TRSz-beginning at the terminal of the central ofiice battery, front contact 66 of the relay I, wire I38 and I3I, stick contact I62 of the transfer relay TRS, wire I33, the lower winding of the transfer relay TRS to the terminal of said battery. Also, picking up of the slow acting relay I closes the following circuit for the channel time relay CT:-beginning at the terminal front contact 66 of the relay I, wires I30, I3 and I35, front contact 83 of the master relay MR wire I36, winding of the relay CT to the other terminal of this battery 44. The completion of this circuit after a short time effects energization of the channel time relay CT, this relay although slightly slow acting is much quicker acting than are the relays I and I Attention is directed to the fact that the position of the contact I8 of the code repeater relay CRR is determined by the condition of energization of the code relay COR, and since the transfer relay TRS is energized each time a way station is controlled from the central office, and is therefore now energize-d through the front contact 49 of the relay SLR its contact M8 assumes its raised position, and therefore the code relay COR is energized or deenergized depending upon whether its circuit is closed through such front contacts as I42, I45 or IM of the relays 2, 5 and '1 respectively. That is, with relay SLR up, as has been assumed, and during the instant when stepping relay 2 is energized the circuit for the relay COR may be traced as foll0ws:beginning atthe terminal B+, winding of the relay COR, wire 252, front contact I46 of the relay 'I'RS, wires 2II, 2Ill and 289, front contact I42 of the stepping relay 2, wire 288, back contact MI of the stepping relay I, wire 281, front contact 286 of the relay LSR wire 265, back contact 284 of the relay SLR wire 283, back contact 282 of relay SLR, wire 26I, back contact 206 of the relay SLR to the midpoint C of the central office battery. In this connection, attention is directed to the fact that insofar as the first four of these code responsive stepping relays I, 2, 3 and 4 are concerned, the code relay COR can only be energized when the corresponding lever selecting relay, that is, SLR in the present instance, is energized, this because the front contact 286 of the relay SLR is included in the circuits through the front contacts of these relays, such as contact I82 of relay 2. Since, with the relay I energized and its contact MI in its raised position the code relay COR remains deenergize-d, the second impulse transmitted over the stepping circuit will be one of negative polarity, this because, with relay COR deenergized the relay CRR is energized toward the left, which selects relay MR instead of relay MR. thus resulting in energization of the line circuit 9| with current of negative polarity as followsz-beginning at the terminal 13-, back contact 85 of the relay MR wire 86, front contact 84 of relay MR wire 81, front contact 88 of the relay W, wire 89, front contact 9!] of the push button PB, wire 9| including the various line relays LR, LR and LE to the common return wire C connected to the midpoint of the central oflice battery. With the channel time relay CT energized the energizing circuit for the master relay MR is broken at the-back contact 1! of the relay CT, so that as soon as the relay MR assumed its deenergized position the following circuit for the code repeating relay CRR is completedt-beginning at the terminal (13-), back contact I56 of the relay COR, wire I5I, upper winding of the relay CRR, wires I52, and I53, front contact I54 of the relay CT, wire I55, back contact I56 of the relay MR wire I5'I, back contact I58 of the relay MR to the middle connection C of the battery 92. The relay CRR will not be operated in response to the closure of the circuit just traced, because it already assumes its left hand negatively energized position. The master relay MR having been deenergized in responseto the picking up of the relay CT will of course by the dropping of its contact 83 again deenergize the channel time relay CT, and in so doing will effect reenergization of the master relay MR thus causing the second impulse of negative polarity to be applied to the stepping circuit.

Bearing now in mind that the stepping circuit was momentarily deenergized, thereby causing the line relays LR, LR LR etc., to temporarily assume their middle position, let us observe what transpires at both the central office and the way station shown in Fig. 2 during the period of deenergization of the stepping line. Referring first to Fig. 1B, and remembering sponsive stepping relay I is still energized through its stick circuit, deenergization of the line relay LR breaks this stick circuit at the contact I88 of the line relay LR, but another stick circuit for this relay I is completed which may be traced as follows:beginning at the terminal contact I88 of the line relay LR in its pendent position, wires 2| and I6I, winding of the half-step relay IA, wire I62, front contact I63 of the relay I, wires I88 and II, winding of the relay I to the other terminal The completion of this auxiliary stick circuit for the relay I, which includes the winding of the relay IA, will of course affect energization of the relay IA thereby closing the front contact I64 of the relay IA. As already explained, after momentary deenergization of the stepping circuit this stepping circuit is reenergized with current of negative polarity and with the relay IA now energized, the following circuit for the relay 2 is completed upon movement of the line relay LR to its left hand negative position:-beginning at the terminal wire 94, contact 95 of the relay LR in its left hand position, wire 86, contact 91 of the relay I raised, wires I65 and I66, front contact I61 of the relay I, wire I68, front contact I64 of the relay IA, wire I69, winding of the relay 2, wires I18 and 25, front contact 68 of the relay I, to the terminal of the same battery.

In practice, the half-step relays IA, 2A, 3A, 4A and 5A will be slightly slower dropping than their associated relays I, 2, 3, 4 and 5, this in order to assure that the stick circuit for the code responsive relay which does not include a half step relay cannot be reclosed before the other stick circuit that the code refor suchcode responsive relay including the halfstep relay is broken, this to assure dropping of the code responsive relays, such as I, 2, 3, etc., as soon as the stepping circuit is energized after having been deenergized following the picking up of such code responsive stepping relay. In other words, movement of the line relay LR to its left hand position effects picking up of the relay 2 but also effects deenergization of the relays I and IA, this because both of these stick circuits for the relay I are opened when the line relay LR assumes its left hand position during the second impulse of a particular code cycle.

The relay 2 having now been picked up, is stuck up through the following stick circuit:--beginning at the terminal contact I08 of the relay LR in its left hand position, wires I09, 22 and I12, back contact I13 of the relay 2A, wire I14, front contact I15 of the relay 2, wires I16 and I11, winding of the relay 2, wires I10 and 25, front contact 66 of the relay I, to the other terminal of the same battery.

Referring now to Fig. 2, substantially the same operation as just explained in connection with Fig. 1B takes place. During deenergization of the line relay LR the auxiliary stick circuit for the code responsive stepping relay I is completed, and may be traced as follows:-beginning at the terminal contact 6 of the relay LR assuming its pendent position, wires I and I8I, winding of the half-step relay IA wire I82, front contact I83 of the relay I wires I23 and I06, winding of the relay I to the other terminal of the same battery. The completion of this circuit of course results in the picking up of the half-step relay I A and closure of its contact I85. The apparatus atthe way station of Fig. 2 remains in its present condition until the line relay LR moves from its pendent position, and since, as has already been explained, the stepping circuit is energized with current of negative polarity on its second step causes the line relay LE to move to its left hand position, thereby completing the following circuit for the code relay 2 :--beginning at the terminal contact I 02 of the line relay LR assuming its left hand position, wire I03, front contact I04 of the relay I wire I86, front contact I81 of the relay I wire I88, front contact I of the relay IA wires I89 and I90, winding of the relay 2 wires I9I and I92, front contact I93 of the relay P, to the terminal of the same battery.

With the code responsive stepping relay 2 once energized its following stick circuit is closed to maintain it energized in spite of the dropping of the relays I and IA which occurs shortly after the line relay LE moves from its deenergized position. This stick circuit for the relay 2 may be traced as follows:beginning at the terminal of the local way station battery, contact II 6 of the relay LR toward the left, wires H1 and I94, back contact I of the relay 2A wire I96, front contact I91 of the relay 2 wires I98, I99 and I90, winding of the relay 2 wires I9I and I92, front contact I93 of the relay I 'to the other terminal Attention is now directed to the fact that had the second impulse transmitted over the stepping circuit been an impulse of positive polarity neither relay 2 nor the relay 2 would have been picked up in response to this second impulse, this because by operation of the line relays LR and LR to the right, with the relays, I, IA, I and IA energized, the circuits for the relay 2 and 2 completed by movement of the contact 95 of the relay LR and contact I 02 of the relay' LR to the right are not energized, because both ends of the circuit completed are connected to the same terminal, namely the terminal of the battery. In other words, these code stepping relays will only step along in response to energization of the stepping circuit if the various impulses are of the proper polarity. Furthermore, if this second impulse had been an impulse of positive polarity the relays I and IA of Fig. 1B and the relay I and IA in Fig. 2 would have been deenergized, the same as they were when an impulse of negative polarity was transmitted, so that no relays of these groups of stepping relays could thereafter have been energized in the same cycle, this because the relays I and I are in their raised position and with all of the stepping relays down no circuits can be completed for energizing any of the relays in these groups of code responsive stepping relays.

Refering now to Figs. 1A and 1B, attention is directed to the fact that, with the code responsive stepping relay 2 in its energized position, a circuit is completed for the code relay COR, which may be traced as fol1ows:beginning at the midpoint of the battery 92 (see Fig. 1A) to the common return wire C, through back contact 200 of the relay SFR, wire 20I, back contact 202 of the relay SLR/ wire 203,back contact 204 of the relay SLR wire 205, front contact 206 of the relay SLR which now assumes the energized position, wire 201, back contact I4I of the relay I, wire 208, front contact I42 of the relay 2, wires 209, 2I0 and 2I I, front contact I40 of the transfer relay TRS (still held stick and also held through front contact 49 of relay SLR wire 2I2, winding of the code relay COR, to the terminal (3+) of the battery 92. The completion of this circuit picks up the contacts of the relays COR, but the code repeater relay CRR will not be operated until the channel time relay CT has been energized, and has opened the contact 11 to effect deenergization of the master relay MR and this master relay has in turn dropped and closed its contact I56. When this occurs the following circuit for the code repeater relay CRR is closedz-beginning at the terminal (B+) of battery 92, front contact 2I5 of the relay COR, wire 2I6, lower winding of the relay CRR, wire I53, front contact I54 of the relay CT, wire I55, back contact I56 of the relay MR wire I51, back contact I58 of the relay MR to common return wire C, connected to the mid-point of the same battery.

The completion of this circuit effects opera" tion of the code repeater relay CRR to its right hand dotted position, thereby causing closure of the following circuit as soon as the channel time relay CT again assumes its deenergized position:beginning at the terminal front contact 15 of the control relay W, wire 16, back contact 11 of the relay CT, wire 18, contact 19 of the relay CRR in its right hand position, wire 2I1, back contact 2I8 of the relay MR wire 2I9, winding of the master relay MR to the other terminal of the same battery. As soon as the relay MR assumes its energized position in response to the completion of the circuit just traced, the stepping line 9| is energized by current of positive polarity through the following branch leading to this stepping circuitz-beginning at the terminal (3+) of the battery 92, front contact 229 of the relay MR wire 22L back contact 84 of the relay MR wire 81, front contact 88 of the control relay W, wire 89, push over the stepping 'button contact 90, through the stepping circuit With the stepping line 9| energized by current of positive polarity the line relays LR, LE and LE are operated to their right hand position. Referring first to Fig. 1B, and bearing in mind that the line circuit was momentarily deenergized, and that during this time of deenergiza tion the half-step relay 2A was picked up by completion of the following circuit-beginning at the terminal contact I08 of the relay LR assuming its pendent position, wires 2| and 224. winding of the relay 2A, wire 225, front contact 226 of the relay 2, wire I11, winding of the relay 2, wires I10 and 25, front contact 66 of the relay I, to the other terminal (-1-) of the same bat tery. Further, that with the relay LR now moved to its right hand position the following pick-up circuit is closed for the code responsive stepping relay 3:--beginning at the terminal. of the central office battery, Contact 95 of the line relay LR in its right hand position, wire 96, front contact 91 of the relay I, wires I and IE6, back contact I61 of the relay I, wire 22%, front contact 229 of the relay 2, wire 232, front contact 23I of the relay 2A, wire 232, winding of the relay 3, to the other terminal of the same battery. The completion of this circuit will of course pick up the relay 3 and complete the following stick circuit for this relayz-beginning at the terminal contact 233 of'the relay LR assuming its right hand position, wires 234, 24 and 236, back contact 231 of therelay 3A, wire 238, front contact 239 of the relay 3,

wires 240 and 2M, winding of the relay 3, to;

the other terminal of the same battery. It is of course understoodv that with the line relay LR now assuming its right hand position that the relays 2 and 2A will be both deenergized, and this also would have been the case had the impulse been an impulse of negative polarity.

Let us now observe how deenergization. of the stepping circuit after the second impulse and reenergization of the stepping circuit bya current of positive polarity will effect energlzation of the code responsive stepping relay 3 in Fig. 2 of the drawings. Deenergization of the line relay LR after the second impulse transmitted circuit effects closure of .the auxiliary stick circuit for the relay 2 which auxiliary stick circuit includes the relayZA and may be traced as follows:--beginning at 1 the terminal contact MB of the relay LE in its pendent position, wires I80 and 243, winding of the relay 2A wire 244, front contact 245 of the relay 2 wires I99 and IQll, winding of the relay 2 wires I! and I92, front contact. N3 of the relay 1 to the other terminal battery.

As already explained the third impulse impressed upon the stepping circuit is an impulse of positive polarity and this impulse effects energization of the code responsive stepping relay 3 through the following circuit:--beginning at the terminal contact I02 of the relay LR assuming its right hand position, wire H13, front contact I04 of the relay 1 wire E86, back contact I81 of the relay I wire 241, front contact 248 of the relay 2 wire 249, front contact 250 of the relay 2A wire 25I winding of the relay 3 to the other terminal of the same battery.

As thus far described the third impulse, namely an impulse of positive polarity, has been transmitted and the code responsive relays 3 and 3 have been energized in response to the transof the same.

mission of this impulse. Referring now to Figs. 1A andv 1B attention is directed to the fact that with the relay 3 energized and the relay 2 deenergized, the circuit heretofore traced for the code relay COR is broken at the back contact I43 of relay 3, so that the relay COR assumes its deenergized position, in which position its contact I59 is reclosed, thereby tending to operate the code repeater relay CRR back to its normal left hand position, but this does not occur until the channel time relay CT has been energized and has effected deenergization of the master relay MR. and closure of its contact I58. When this occurs the code repeater relay CRR is moved to its left hand position, thereby establishing a circuit for the master relay MR as soon as the channel time relay CT again assumes its deenergized position and closes its contact 11. Picking up of the master relay MR will, of course, cause the application of an impulse of negative polarity to the stepping circuit, for reasons heretofore given.

Referring to Fig. 1B, the momentary deenergization. of the stepping circuit just preceding the fourth impulse, of course, effected energization of the half-step relay 3A through the following circuit:-beginning at the terminal contact 233 of the relay LR assuming its pendent position, wires 23 and 258, winding of the relay 3A, wire 251, front contact 258 of the relay 3, wire 5 24!, winding of therelay 3, to the other terminal of the same battery.

Similarly, this momentary deenergization of the stepping line effected picking up of, the relay 3A in Fig. 2 of the ing circuit:-beginning at the terminal plus, contact 26B of the relay LE assuming its pendent position, wires 26! and 262, winding of the relay 3A wire 263, front contact 264 of the relay 3 wire 265, winding of terminal of the way station battery.

Referring now again to Fig. 1B of the drawings the transmission of the fourth impulse, which is an impulse of negative polarity, completes the following pick-up circuit for the relay 4:-bei ginning at the terminal wire 94, contact 95 of the relay LR in its left hand position, wire 95, front contact 91 of the relay 1, wires I55 and H35, back contact H51 of the relay l, wire 228, back contact 229 of the relay 2, wire 281, front contact 258 of the relay 3, wire 259, front contact 210 of the relay 3A, wire 21l, winding of the relay 4, wires 212 and 25, front contact 65 of the relay I, to the other terminal of the same battery.

Similarly, referring to Fig. 2, the code responr sive stepping relay 4 is energized through the following circuit when the line relay LR assumes its left hand position during the fourth impulse of the particular code now being transmitted:- beginning at the terminal contact m2 of the line relay LR in its left hand position, wire Hi3, front contact I04 of the relay 1 wire I86, back contact I81 of the relay I wire 241, back contact 248 of the relay 2 wire 214, front contact 2'l5 of the relay 3 wire 215, front contact 211 of the relay 3A wire 218, winding of the relay 4 wires 219 and I92, front contact I93 of the relay 1 to the other terminal of the same battery.

The relay 4 will obviously be stuck up through the following stick circuit:-beginning at the terminal contact m8 of the relay LR in its left hand position, wires H19, 2? and 280, back contact 2! of the relay 4A, wires 282, front contact 283 of the relay 4, wires 284 and 285, winding of the relay 4, wires 212 and 25, front contact drawings through the follow- :1;

the relay 3 to the other 1 the other terminal of the same battery.

Referring now to Fig. 1B of the drawings, attention is directed to the fact that the lifting of contact I44 of the stepping relay 4 does not in any way effect the circuit for the code relay COR,

responsive stepping relays 5 and 5 will be energized.

Just preceding this fifth impulse on the stepping circuit, deenerglzation of the stepping cirthe following circuit-beginning at the terminal contact I08 of the line relay LR assuming its pendent position, wires 2I and 294, winding of the relay 4A, wire 295, front contact 296 of the relay 4, wire 285, winding of the relay 4, wires 272 and 25, front contact 66 of the relay I, to

the other terminal of the battery; and similarly this momentary deenergization of the stepping circuit causes the relay 4A (see Fig. 2) to be energized through the following circuit:beginning at the terminal contact II6 of the relay LR assuming its pendent position, wires I80 and I98, winding of the relay 4A wire 299, front contact 300 of the relay 4 wire 292, winding of the relay 4 wires 219 and I 92, front contact I 93 of the relay I to the other terminal of the same battery.

The half-step relays 4A and 4A have thus taken contact 95 of the relay LR to the left, wire 96, front contact 9'! of the relay I, wires I65 and I66, back contact I61 of the relay I, wire 228, back contact 229 of relay 2, wire 261, back contact 2658 of relay 3, wire 302, front contact 303 of the relay 4, wire 304, front contact 305 of the relay 4A, wire 306, winding of the and 25, front con-tact 66 of the relay I, to the SIG, front contact 3 of the relay 4A wire 3| 2,

windingof the relay 5 wires 3I3 and I92, front contact I93 of the relay I to the other terminal of the same battery.

The relay 5 now assuming its energized position following stick circuit:beginning at the terminal contact II6 of the relay LR to the left (see Fig. 2), wires III and32I, back contact 322 of the relay 5A wire 323, front contact 324 of the relay 5 wires 325 and 326, winding of the relay 5 wires 3I3 and I92, front-contact I 93 of the relay I to the other terminal The operation thus far described has concerned applies the impulses ofplus, minus and plus for energizing the relays 6 1 and 8 respectively. Referring to Fig. 13 itis noted that with the relay 5 picked up, as is now the case, the closure of its contact I45 applies current to the code relay relay CT has picked up and has effected deenergi- As soon as this With the line relay LR now operated to its right hand position in response to the sixth imtraced in the drawings and including the wire 328, the front contact 329 of the relay 5, and the Winding of the relay 5, the relay 6 is picked up through the following oircuitz-beginning at the terminal contact 95 of the relay LR assum- In the same wa the deenergization of the stepping line just preceding the sixth impulse causes the relay A to pick up and to complete the following circuit:--beginning at the terminal contact II6 of the relay LR assuming its deenergized position, wires I86 and 338, winding of the relay 5A wire 339, front contact 348 of the relay 5 wire 326, winding of the relay 5 wires 3I3 and I62, front contact I93 of the relay I to the other terminal With the line relay LR operated to its right hand position due to the sixth impulse of the particular code transmitted, this being an impulse of positive polarity, causes the relay Ii to be energized through the following circuit:-beginning at the terminal contact I82 of the relay LR assuming its right hand position, wire I03, front contact I04 of the relay 1 wire I86, back contact I81 of the relay I wire 241, back contact 248 of the relay 2 wire 214, back contact 215 of the relay 3 wire 308, back contact 399 of the relay 4 wire 34!, front contact 342 of the relay 5 wire 343, front contact 344 of the relay 5A wire 345, winding of the relay 6 wire 346, back contact 341 of the relay 1 to the other terminal of the same battery.

Referring now to Fig. 1B of the drawings, it being understood that the relays 5 and 5A were deenergized in response to the energization of the relay 6, the code relay COR (see Fig. 1A) is again deenergized, this because the contact I45 of the relay 5 is now assuming its retracted position opening the following circuit for relay COR:- 13+, CUR, 2I2, I48, 2H, 2H], I45 and C. Under these conditions, after a momentary deenergization of the stepping circuit, and with the code relay COR now deenergized, the code repeater relay CRR is again operated to its normal left hand position, thereby causing the seventh impulse to be applied to the stepping circuit, which is an impulse of negative polarity. With the relay LR now operated to its left hand position in response to the impulse of negative polarity causes the stepping relay 1 to be picked up through the following pick-up circuit:-beginning at the terminal wire 94, contact 95 of the line relay LR to the left, wire 36, front contact 91 of the relay I, wires I65 and I63, back contact I61 of the relay I, wire 228, back contact 229 of the relay 2, wire 261, back contact 268 of the relay 3, wire 362, back contact 333 of the relay 4, wire 339, back contact 33I of the relay 5, wire 358, front contact 35! of the relay 6, wire 352, winding of the relay 1, wire 353, back contact 354 of the relay 5, wires 355 and 25, front contact 63 of the relay I to the other terminal of the same battery. Picking up of this relay 1 causes it to be stuck up through the following stick circuit:beginning at the terminal front stick contact 336 of the relay 1, wire 351, lower winding of the relay IR (see Fig. 1A), wires 358 and 352, winding of the relay 1, wire 353, back contact 354 of the relay 8, wires 355 and 25, front contact 66 of the relay I to the other terminal It should be noted that the stick circuit for the relay 1 includes the lower winding of the indicating relay 1R (see Fig. 1A). This provision is made so that each energization of the relay "I will cause the indicating relay IE to be operated to its normal negative position, this relay under certain conditions being operated to its right hand position during the energization of the relay 6, which conditions involve the occupancy of the detector track circuit at the west end of the passing siding PS, all in a manner as is hereinafter described.

'lay 3 wires 331 and Fig. 2, and bearing in mind that the relay 6 is stuck up through a stick circuit including the wire 360 and the stick contact 36I of this relay 6 the relay 12 is picked up through the following circuit during the seventh impulse of the particular code cycle, which impulse is an impulse of negative polarityz-beginning at the terminal contact I62 of the line relay LR to the left, Wire I03, front contact I64 the relay I wire I86, back contact I31 or the relay I wire 241, back contact 248 of the relay 2 wire 214, back contact 215 of the relay 3 wire 393, back contact 369 of the relay 4*, wire 34I, back contact 342 of the relay 5 wire 362, front contact 363 of the relay 6 wire 364, Winding of the relay wire 5-355, back contact 366 of the re- I92, front contact I93 of the relay I to the other terminal Referring now to Fig. 13 it should be noted that with the relay 1 energized, the lifting of its contact I41 completes an energizing circuit for the code relay COR (see Fig. 1A) readily traced in the drawings, and that with this code relay COR energized the code repeater relay CRR is operated to its right hand position during the momentary energization of the channel time relay CT, so that when this relay CT again assumes its deenergized position the relay MR is energized and the stepping circut is energized by an impulse of positive polarity.

This impulse of positive polarity operates the line relays LR, LR. and LR to their right hand position, thereby completing the following energizing circuit for the relay 8 (see Fig. 13) :be ginning at the terminal contact 95 of the relay LR to the right, wire 96, front contact 91 of the relay I, wires I65 and IE6, back contact I61 of the relay I, wire 228, back contact 223, wire 261, contact 268, wire 362, contact 393, Wire 339, contact 33I, wire 356, back contact 35I, wire 339, front contact 316 of the relay 1, wire 31I, winding of the relay 8, to the other terminal With the relay 8 picked up it is stuck up through a stick circuit including its stick contact 354 and the front contact 66 of the relay 1.

Referring now to Fig. 2 the relay 8 is picked up in response to the eighth impulse of the particular code cycle under consideration, which is an impulse of positive polarity, through the following pick-up circuit-beginning at the terminal of the local battery, contact I32 of the relay LE to the right, wire I63, front contact I94 of the relay I wire I86, contact I31, wire 241, contact 248, wire 214, contact 215, wire 368, contact 339, wire 34I, contact 342, wire 362, contact 363, wire 313, front contact 314 of the relay 1 wire 315, winding of the relay 8 to the other terminal of the same battery. With this relay 8 once picked up it is stuck up through a stick circuit including its stick contact 335 and the front contact I93 of the relay 1 With the relay 8 now energized, its back contact 58 is open and the stick circuit for the relay SLR and the relay W (see Fig. 1A) is broken at the contact 58, so that these relays SLR and W assume their deenergized position, thereby, among other things, breaking the stepping circuit at the contact 88 of the relay W and breaking the energizing circuit for the master relay 2 at the front contact 15 of the relay W; the relay CR the relay I picked up. With the stepping circuit deenergized the relay I and I will, after a short period of time, assume their deenergized positions and in so doing will effect deenergization Referring now to was of course deenergized as soon as front contact 38I of the relay 5, wire 382, back contact 383 of the relay 6, wire 384, back contact 385 of the relay I, wire 386, back contact 381 of the relay 8, wires 388 and 389, front contact 390 of the relay CT, wire 39I, back contact 392 of the relay MR wire 393, back contact 394 of the relay MR wires 395 and 396 and I26, front 8, also bieaks the stick circuit for the transfer C n a I23 0 t re ay message Wi e W relay TRS causing it to be deenergized d 397 (see Fig. 2) front contact I29 of the relay I wire 398, back contact 399 of the relay 8 wire 40I, back contact 482 of 403, back contact 484 of the front contact 408 of the relay 5 wire 401, winding of the direction relay DB to the common return wire C leading back to the central ofiice and connected to the mid-point of the battery 92.

Similarly, the signal relay SR its right hand the relay 1 wire relay 8 wire 405,

is operated to position through the following cirthe wiring for the control of the relays II, IIA, I2, I2A, I3 and I3A is exactly the same as that of the wiring for the relays I, IA, 2, 2A, 3 and 3A, respectively, and that the relays II, IIA, I2, I2A, I3 and I3A were sequentially energized during the first three impulses of the code considered. Attention is directed to the fact that the polarity signs to the left of the relays I I, I2 and I3 are exactly the same as that I, 2

contact 387 of the relay 8, wires 388 and 389, 398 of the relay CT, wire 39I, back contact 392 of the relay MR Wire 393, back contact 394 of the relay MR wires 395, 396 and I26, front contact I28 of the relay I, message wire 498, Wire 397, front contact I29 of the relay I wire 398, back contact 399 of the relay 8 wire 40I, back contact 402 'of the relay 1 wire 403, front contact 404 of the relay 6 wire 4I2, winding of the signal relay SR to the common return wire C connected to the mid-point of the battery 92.

and l are energized the following circuit for the switch machine re- Since the relay I4 requires an impulse of posilay SW is closed:-beginning at the terminal switch machine contact SML assuming its left hand position, wire 4M, front contact 385 of the relay I, wire 386, back contact 381 of the relay 8, wires 388 and 389, front contact 390 of the relay CT, wire 39I, back contact 392 of the relay MR wire 393, back contact 394 of the relay MR wires 395, 396 and I29, front contact I28 of the relay I, message wire 490, wire 391, front contact I29 of the rethe relays I3 and I 3 and 3A dropped,

3A dropped when the relays no relays could be picked up in the relay group shown in the lower half of lay I wire 398, back contact 399 of the relay Fig. 1B when code No. 12, which was heretofore 8 wire 48I, front contact 402 of the relay I considered, was transmitted to the various way wire 4I5, winding of the relay SW to the comstations by the central oflice equipment In this mon return wire 0 connected to the the battery 92.

The successive completions of the three channel circuits just traced, effects operation of the relays SR and SW to their dotted positions, but leaves the direction relay DR in its normal east bound position. Operation of the switch machine mid-point of for the second step, four relays for the third step, and so on, so that there would be sixteen relays for the fifth step, thus taking care of all the codes given in the table above.

Having now explained how the code responsive relay SR assuming its proceed position the takestepping relays I to 8 and I and 8 are sequensiding signal 39 is cleared, thereby directing the tially picked up when code No. 12 is applied to movement of the train into the sidetrack of the he t pp ng circuit, passing siding PS. switch machine SM and the signals associated therewith are controlled in response to the movedirection relay DB (see Fig. 2) is closed:-beof an. over-lap between the channel circuit ginning at the terminal (B-I of the battery 92, lever SL3 (seeFigr lA) to the right, wire 380,

initiating quired to select Code dictation for i'n-coming station selection Let us now see how an in-coming message is transmitted and let us assume that the east bound train accepts the take-siding signal 36 and moves into the sidetrack of the passing siding PS. As this train treads upon the detector track circuit containing the track relay TR this track relay TR is deenergized and in so doing closes its contact 4I1 and drops its contact 4I8, the latter of which results in momentary dropping of the relay M since during the pole changing of its circuit the magnetism moves through zero allowing its contact M9 to be momentarily closed. Momentary closure of the contact 459 picks up the repeater stick relay FR which when once picked up sticks up through the following stick circuit:-beginning at the terminal (-1-), back contacts 429 of the relay 8 wire 42!, front contact 422, wire 423, winding of the relay FR to the other terminal Picking up of this repeater change stick relay FR closes the following initiating circuit for the central office equipment:-beginning at the terminal (13+) of the battery 92 (see Fig. 1A) winding of the field relay FR, wire 424, push button contact PB, wire 425, back contact I28 of the relay 1, message wire 499, wire 391 (see Fig. 2), back contact I29 of the relay 1 wire 425, front contact 421 of the relay FR to the common return wire C connected to the midpoint of the battery 92.

Completion of the circuit just traced picks up the relay FR (see Fig. 1A) and in turn completes the following circuit for the upper coil of the selector field relay SFR:-beginning at the terminal b ack contact 50 of the relay RU, wire 430, back contact 43I of the relay R11 wire 432, back contact 433 of the relay RL wire 434, front contact 435 of the relay FR, upper winding of the relay SFR to the other terminal of the same battery. With the relay SFR once picked up it locks out the relays SLR? SLR SLR etc., and completes its following stick circuit:-beginning at the terminal (-1-), back contact 53 of the relay 8, wire 59, back contact 69 of the relay l8, wires SI and 69, front contact 435 of the relay SFR, lower winding of this relay SFR to the other terminal With the relay SFR energized and its front contact 431 closed the starting relay CR is energized through the circuit heretofore traced except that it includes the front contact 431 of the relay SFR instead of the contact 65 of the relay SLRF. Picking up of the starting relay CR closes the pick-up circuit for the relay W heretofore traced, which relay W is then stuck up in a manner as already explained hereinbefore. Picking up of the control relay W closes the stepping line at contact 83 and closes an energizing circuit for the master relay MR which in turn through the lifting of its contact 84 applies an impulse of negative polarity to the stepping circuit, so that the line relays LR, LE LE etc., are all operated to the left.

At this point inthe operation of the system it should be remembered that the way stations are selected by code and that the central office equipment has not yet been informed what code is rethe particular way station, namely, the way station shown in Fig. 2, so that this way station may transmit an indication to the central office informing the operator that the east bound train has tread upon the detector track circuit containing the track relay T3 It may be pointed out here that the code which is to be transmitted will be dictated step by step, so to speak, by the apparatus shown in Fig. 2, this dictation of the code being accomplished by short circuiting, or not short circuiting, as the case may be, the message wire to the common return wire at a particular step when the next following impulse on the stepping line shall be respectively of plus polarity or of minus polarity. In other words, circuited on step one then step two will be of positive polarity, and if the message circuit is not short circuited on step one then step; two will be of negative polarity.

Referring now to Fig. 2 it will be noted that the contact 44I has been provided for this purpose, and that lifting of the contact 440 will not short circuit the message wire to the common wire, whereas lifting of contact 44I will short circuit the message wire 499 to the common wire, so that the second impulse transmitted over the stepping circuit will be of negative polarity, whereas the third step will be of positive polarity, it being further understood that the transfer relay TRS assumes its deenergized position and that the code relay COR is included directly in series with the message circuit and a source of energy, so that had the message circuit been connected to the common return wire the code relay COR would have been up, but this was not the case so that the second impulse transmitted over the stepping circuit is of negative polarity, and the relays 2 and 2 will pick up.

With the relay 2 now picked up and the contact 421 of the field relay FR closed, the following code-dictating circuit is completed for the code relay COR:-beginning at the terminal (3+) of the battery 92, winding of the relay COR (see Fig. 1A) wire 2I2, back contact I40 of the transfer relay TRS, wires 445, 396 and I25, front contact I28 of the relay I, message wire 409, wire 391 (see Fig. 2) front contact I29 of the relay 1 wire 398, back contact 399 of the relay 8 wire 49L back contact 492 of the relay 1 wire 493, back contact 494 of the relay 6 wire 4%, back contact 406 of the relay 5 wire 446, back contact 443 of the relay 4 wire 441, back contact 442 of the relay 3 wire 448, front contact 44I of the relay 2 wire 426, front contact 421 of the relay FR to the common return wire C connected to the mid-point of the battery 92.

The completion of this circuit during the second step of the particular code transmitted will, when the master relay MR drops close the circuit for the lower winding of the code repeater relay ORR, thereby operating it to its right hand dotted position, after which as soon as the channel time relay CT assumes its deenergized position and closes its contact 11, it will complete an energizing circuit for the master relay MR which when energized applies an impulse of positive polarity to the stepping circuit, thereby operating the line relays to the right and picking up the relay 3 and 3 in a manner as already explained.

Picking up of the relay 3 by lifting its contact 442 does not connect the message circuit to the common return wire, and therefore the code relay COR (see Fig. 1A) remains deenergized, it having been deenergized as soon as the relay 2 dropped, from which it is readily understood that the fourth impulse transmitted will be an impulse of negative polarity, this because the code repeater relay CRR is returned to its left hand normal position during the channel time between steps 3 and 4.

if the message circuit is short Referring again to Fig. 2 of the drawings and bearing in mind that the relay 4 is next energized and since its contact 443 does not connect the message wire 400 to the common return wire C, it is apparent that the code relay COR. remains deenergized and the fifth impulse transmitted is one of negative polarity.

The relays 5 and 5 are now energized, and referring to Fig. 1B attention is directed to the fact that closure of contact 45! of the relay 5 corn pletes an energizing circuit for the transfer relay TRS, which may be traced as follows:-beginning at the terminal of the central oflice battery, front contact 66 of the relay I (see Fig. 1B), Wires 25 and 45L front contact 459 of the relay 5, wires G52 and 569, middle coil of the transfer relay TBS, to the terminal of said battery. The completion of this circuit picks up the transfer relay TBS, and with this transfer relay TRS once picked up it is stuck up through its stick circuit heretofore traced and including its stick contact I32 and the front contact 66 of the relay I.

Picking up of the transfer relay 'IRS shifts its contact I ifl so that the code relay COR is no longer controlled by the condition of the message circuit but is controlled in accordance with the contacts of the relays 5, 6 and I as shown in Fig. 1B of the drawings, in exactly the same manner as the code relay COR was controlled by these relays 5, 6 and I when the system was initiated by a lever movement. In other words, when a particular way side station is to be selected in response to a lever movement the entire code is determined by contacts on the central ofiice group of relays corresponding to that way station. When, however, a particular way station is to be selected in response to initiation from the field, the code that is sent out is dictated one step at a time during the way station selecting portion of the code, namely the first five impulses in the particular arrangement shown of the code which select the way station, and thereafter since the corresponding group of central office relays have been definitely determined the code is thereafter determined by the channel selecting relays, such as the relays 5, 6, I and 8 of the central oflice equipment.

Let us now see how the central office is informed of the fact that the track relay TR is deenergized. It is, of course, understood that the relays 8 and 8 are simultaneously energized during the eighth impulse of the particular code under consideration, and at this time the following message circuit for controlling the indicating relay IR (see Fig. 1A) is closed:beginning at the terminal (B+) of the battery 92, upper winding of the indicating relay IE wire 455, front contact 381 of the relay 8, wires 388 and 389, front contact 390 of the relay CT, wire 392, back contact 392 of the relay MR Wire 393, back contact 394 of the relay MR wires 995, 396 and I26, front contact I28 of the relay I, message wire 4G0, wire 391 (see Fig. 2), front contact I29 of the relay I wire 398, front contact 399 of the relay 3 wire 456, back contact M7 of the relay TR to the common return wire C connected to the mid-point of the battery 92. The completion of this circuit operates the indicating relay IE to its right hand dotted position, thereby closing an energizing circuit for illuminating the indicating lamp IW, readily traced in the drawings. In this connection it should be remembered that the relay 1R as hereinbefore explained, is operated to its left hand position upon each energization of the relay 1, this because the lower winding of the indicating relay IR is included in series with the stick circuit for the relay Ii, from which it appears that with the track relay PR energized the indicating relay IE will be operated to and remain in its left hand position.

Code superiority for z'n-comz'ng station selection Having now explained how the apparatus at a particular way station, the way station shown as Fig. 2, having been used as an example, may dictate the code for selecting that particular way station to transmit an in-coming message, let us now observe what would happen if several way stations were trying to transmit a change of indication and dictate a code at the same time. Let us bear in mind that if a way station does nothing toward dictating a plus impulse, a negative impulse will be applied to the stepping circuit in the next succeeding step. but if a way station connects the message wire to the common wire the next impulse will be of positive polarity. Let us also bear in series of code responsive stepping relays is so constructed that if a particular impulse in a code is of the wrong polarity the entire series of relays will be rendered inoperative and will not again be able to respond toan impulse until a. new code cycle of impulses is initiated. With these facts in mind, it is of course apparent that the particular way stations which dictate a positive impulse for the next step, will be accommo dated by an impulse of plus polarity resulting in the picking up of their next code relay, and since the next code relay of the other way stations under consideration require an impulse of negative polarity, such other way stations will drop out, thus leaving the Way stations which have dictated a positive impulse in a condition to dictate a succeeding impulse. In this way more and more way stations will be eliminated, until finally the dominating one of the way stations endeavoring to transmit an indicating to the central ofiice will be selected.

Referring now to the table of codes heretofore given, it is apparent that code No. 1 which dictates four positive impulses for the second, third, fourth and fifth step during its first, second, third and fourth step, respectively, will dominate code No. 2 in that the second code dictates only three positive impulses for the second, third and fourth step during the first, second and third step, respectively, this second code requiring an impulse of negative polarity for the fifth step. The same theory applies to every succeeding code With respect to its adjacent code, as can be readily ascertained by observing the number and order of plus and minus impulses in each code. For instance, code No. 15 is superior to code 16 in that it dictates a code of positive polarity during the fourth step, so that the 5th step will be one of positive polarity, whereas code No. 16 is satisfied if all the impulses are of negative polarity, this being the most inferior code.

In this connection, let us particularly observe codes No. 12 and No. 10, the apparatus for which is shown in Figs. 2 and 3 respectively. It will be noted that if these two way stations were trying to indicate at the central ofiice a change in traflic conditions simultaneously, their apparatuses would be initiated simultaneously. With both of the change stick relays FR? and FR up, the contacts I (see Fig. 2), 438 and 439 (see Fig. 3), will be able to control the code relay COR and call for a positive impulse for the next mind, that each the way station. selecting step of the code. During the second step of the code under consideration (which code is not yet definitely determined) the contacts 438 and 441 of relays 2 and 12 respectively, will be up energizing the relay COR, thus dictating an im pulse of positive polarity for the third step.

During the third step the contact 439 of relay I3 will be up, effecting energization of the relay COR, thus dictating an impulse of positive polarity for the fourth step. This impulse of positive polarity, constituting the fourth step, will effect picking up of the relay 14 (in a manner as hereinafter described) but will not effect picking up of the relay 4 as is also true of the relays I4 and 4, respectively. It is thus seen that the apparatus of Fig. 3 is connected to respond to a superior code (code No. 10) than is the apparatus shown in Fig. 2 (which responds to code No. 12). In other words the code dictating contacts, such as contacts 438, 439 and 441, are all connected in multiple, when their respective change relays FR and FR are up, so that the closing of such contact is a superior condition to the opening of such contact, in that upon contact closure the desired result is obtained whereas if left open the desired result may ormay not be obtained.

Modifi d way station apparatus Attention is directed to the fact that each of code relays of Fig. 2, such as the relays 1 2 etc. have each associated therewith a half-step relay, such as 1A 2A etc. In the arrangement shown in Fig. 3 of the drawings these half-step relays have been omitted, and a half-step group of relays comprising the even relay E, the odd relay 0, polar relay P has relays E, O and P may be said to be a group of relays which keeps track of the fact whether a particular impulse is an odd impulse or an even impulse in the particular code cycle of impulses transmitted. It is believed that the apparatus in Fig. 3 can be best understood by considering the operation of the apparatus.

Operation of structure in Fig. 3

It is believed sufiicient to point out that the apparatus shown in the lower half of Fig. 1B is a series of relays which respond to the tenth code, and which in response to depression of the push button PB causes transmission of the tenth code, comprising a code of minus, minus, plus, plus and minus. Furthermore, suffice it to say that the relays in the lower half of Fig. 1B are connected exactly the same as are the corresponding relays. in the upper part of Fig. 1B, except that the polarity of the right hand terminal of relay I4 is connected to the minus terminal of the central office battery, whereas the right hand terminal of the relay 4 is connected to the positive terminal of the same battery, and that the two stick circuits leading from the left side of the relay 4 go to a left hand and a neutral contact of the line relay LR; connected to the negative terminal of the battery, whereas the two stick circuits leading from the left hand side of the relay l4 terminate at the right hand side and the neutral point, respec tively, of a contact of the line relay LR connected to the positive terminal of the same battery. Furthermore, that only the contact 142 of the upper series of relays is capable of picking up the code relay CUR, whereas in the group in the lower half of Fig. 1B the contacts 456 and 459 are capable of picking up the code relay COR. The reason for this is obvious in view of explanations heretofore made.

Referring now to Fig. 3 of the drawings, let us observe how the tenth code of impulses is capable of selecting the apparatus shown in Fig. 3. The first impulse of this code is one of negative polarity, and with the line relay LE operated toward the left the following circuit for the odd relay 0 is completed:-beginning at the terminal contact 466 of the relay LE assuming its left hand position, wires 46!, 462 and 463, winding of the relay 0, wires 464 and 465, back contact 466 of the relay E, wire 461, contact 468 of the relay P to the other terminal The completion of this circuit picks up the relay 0 thereby completing the following stick circuit for the relay 02- beginning at the terminal contact 460, wires 461, 462 and 463, winding of the relay 0, wires 464 and 411, stick contact 410 to the terminal Also, picking up of the relay 0 operates the relay P to its left hand dotted position through a circuit including its front contact 412. It is noted that the relay E could not pick up when the relay 0 was picked up because its pi ckup circuit was then open at the contact 468 of the relay P, and that the relay E could not pick up when the relay P operated to its dotted position, because its pick-up circuit was then broken at the back contact 413 of the relay 0.

Also, operation of the line relay LE to its left hand position completes the following pickup circuit for the first code responsive stepping relay, namely the relay lWz-beginning at the terminal contact 415 of the relay LE to the left, wires 416 and 411, back contact 419 of the relay I wires 419 and 480, winding of the relay H wires 48! and 462, front contact 483 of the relay 0 to the other terminal of the same battery. It is of course understood that the stepping wire is momentarily deenergized between the first and the second impulse, both of which are negative, and when this occurs the stick circuit for the odd relay 0 is broken at the contact 466 of the relay LE so that the relay 0 is deenergized. Also, with this relay 0 now deenergized and its contact 483 open and with the slow acting cycle demarking relay now picked up, the relay II is still stuck up through the following stick circuit:-beginning at the terminal front contact 485 of the relay I wire 486, contact 461 of the relay P assuming its left hand position, wires 482 and 481, winding of the relay H wire 48!] and stick contact 488 of the relay H Movement of the line relay LE to its left hand position in response to the second impulse of the code under consideration, closes a circuit for the even relay E, which may be traced as follows:--beginning at the terminal (-1-), contact 466 of the relay LR toward the left, wires 46!, 462 and 489, winding of the even relay E, wires 490 and 491, back contact 413 of the relay 0, wire 492, contact 466 of the relay P, to the other terminal of the same battery. With the relay E now energized and with the contact 415 assuming its left hand position the following pickup circuit for the relay I2 is completed:--beginning at the terminal contact 415 of the relay LR to the left, wires 416 and 411, contact 418 of the relay I to its attracted position, wire 493, front contact 494 of the relay H wire 495, winding of the relay I2 wires 496 and 491, contact 498 of the relay E, to the other terminal (-1-) of the same battery. The relay I2 as soon as it is picked up will of course be stuck up through a circuit readily traced and including its front stick contact 499. Picking up of the relay E will of course cause the relay P to be operated to its left hand position through the medium of a circuit including the front contact 500 of the relay E, so that deenergization of the line relay LR and in turn the even relay E, still leaves a stick circuit for the relay I 2 which includes the stick contact 499 of the relay 12 the contact 481 of the relay P assuming its right hand position and the contact 485 of the relay I The third impulse of the tenth code is an impulse of positive ergized for reasons heretofore given and effects operation of the relay P to its left hand position, and further operation of the line relay LR toward the right completes the following pick-up circuit for the relay 13 beginm'ng at the terminal contact 415 of the relay LE wires 411i and 411, contact'418 of the relay I wire 493, back contact 494 of the relay 1 1 wire 501, front contact 502 of the relay 12 wire 503, winding of wires 504 and 505, front contact stick contact 501. of the line relay LE now effects ofthe odd relay 0, but since the relay P has in the meantime been operated to its left hand position, the following stick circuit for the relay 13 is still intact:-beginning at the terminal (-1-), fro-ntcontact 501 of the'relay 13 wire 558, winding of the relay 13 wires 504 and 505, contact 509 of the relay P assuming its left hand position, wire 510, front contact 511 of the relay I to the other terminal of the local battery. Deenergization of the line relay LR after the third impulse of course drops the odd relayO, and since the fourth impulse of the particular code under consideration is also plus the line relay LR is again operated to its right hand position, and in so doing picks up the even relay E, which effects operation of the polar relay P to the right hand position and with the line relay LE in the right hand position closure of the following pick-up circuit for code responsive stepping relay 14 is effected:-beginningat the terminal contact 115 of the line relay LE toward the right, wires 416 and 411, contact 418 of therelayI ,'wire 493, back contact 494, wire 501, back contact 502, wire 513, front contact 514 of the relay 13 wire 515, winding of the relay 14 wires 516 and 511, front contact 518 of the relay E and. to the other terminal of the battery. The relay 14 will of course be stuck up through a stick circuit readily traced in the drawings and including its stick contact 515 and contact 518 of the relay E. Dropping of the relay E upon deenergization of the line relay LE will of course still leave another stick circuit for Deenergization deenergization the contact 509 of the relay P to theright and the contact 511 of the relay I 'I'he'fifth impulse of the code under consideration is an impulse of negative polarity, and with theline relay LE now operated toward the left, it will of course effect picking up of the odd relay 0, for reasons heretofore given and will also complete the following pick-up circuit for the relay 15 :-beginning at the terminal contact 415 of the relay LR toward the left, wires 416 and 411, front contact 418, wire 493, back contact 494, .Wire 501, backcontact 502,

Wire 513, back contact 514, wire 520, front contact 521, wire 522, winding of the relay 15 wires 523 and 452, front contact 403 of the odd relay 0. Picking up of the relay 15 will of course complete a stick circuit readily traced and including its stick contact 524. Also picking up of the relay 0 will operate the relay P to its left hand position, and with the line relay LE assuming its left hand position, the relay 15 is stuck up through a stick circuit including its stick contact 524, contact 431 of the relay P assuming its left hand position and the front contact 485 of impulse.

The next impulse for the particular code under consideration is an impulse of positive polarity and operates the line relay LE to the right, thereby causing energization of the even relay wire 501, back contact 502, wire 513, back contact 514, wire 520, back contact 521, wire 526, front contact 521 of the relay 15 wire 528, Winding of the relay 16 back contact 529 of the relay l1 and to the other terminal of the battery. With the relay 16 once picked up it is stuck up through the following stick circuit:-

531 and 532, stick contact 533, winding of this relay 16 back contact 529 of the relay 11 and to the other terminal of the battery.

During the channel time following the sixth impulse, the relay LE will of course be deenergized thereby dropping the even relay E, and since the seventh impulse is one of negative polarity, the code responsive relay 11 will be picked up tlnough the following pick-up circuit, the odd relay 0 having been picked up in the meantime:-beginning at the terminal of the local battery, contact 415 of the relay LR wires 416 and 411, front contact 418 of the relay I wire 493, back contact 494, wire 501, back contact 502, wire 513, back contact 514, wire 520, back contact 521, wire 526, back contact 521, wire 535, front contact 536 of the relay 16 wire 531, winding of the relay 11 back contact 538 of the relay 18 wires 539 and 531, front contact 530 of the relay I and to the other terminal plus and including Deenergization of the line relay LR following pick-up circuit, the even relay E having been meantime:-beginning at the terminal of the Way station battery, contact right, wires 416 and 418 of the relay 1 wire 493, contact 494, wire 501, contact 502, wire 513, contact 514, wire 529, contact 52!, wire 525, contact 521, Wire 535, contact 536, wire 540, front contact 541, wire 542, winding of the relay 18 and to the other terminal of the same battery. The relay 18 will of course be stuck up through a circuit readily traced and including its stick contact 538.

A short interval of time after the relay H! has been picked up and stuck up, the stepping circuit will be deenergized at the local ofiice, for reasons heretofore given, thereby deenergizing the various slow acting relays including the relay I and thereby breaking the stick circuit for the relay I8 at the front contact 530 of this slow acting relay I Also, dropping of the relay I through the medium of its contact 530 will restore the polar relay P to its right hand position, so that upon initiation of a new series or code of impulses the odd relay 0 will be the first one of the relays O and E to be picked up, so that the relays O, E and P will count off the even and odd impulses in the same manner as heretofore explained.

Attention is now directed to the fact that the relays DB SR and EiW may be controlled respectively during the channel time when the relays 15 Hi and I7 are energized, and that the indicating relay 1R (see Fig. 1A) may be controlled through the channel circuit which is closed when the relays l8 and 58 are energized, all in a manner as already hereinbefore described in connection with relay 1R Simultaneous communication by the central office with all of the way stations The operator in the central office has of course the necessary information with respect to train movements that he could conveniently announce at any particular way station, or at a ticket ofiice near such way station, the fact whether or not trains are moving according to their time table schedule, whether they are on time or not, whether any special trains or double sections are operating, and in accordance with the present invention the operator may do so by getting in communication with such ticket ofilces through the medium of the selector system. embodying the present invention. In the local office (see Fig. 1A) there is a suitable transmitter 545, which may be either a telephone transmitter or a printing telegraph transmitter, and at each way station (see Figs. 2 and 3) there is provided a receiver 546 and MW, which receivers in the case audible communication is employed is a loud speaker of the usual construction, whereas if printing'telegraph communication is employed these receivers may be printing telegraph receivers of any suitable construction, either printing on tape as does the usual stock ticker or printing successive lines as is done by the ordinary typewriter.

Let us assume that the operator wishes to make an announcement to the various ticket offlees, and in order to do so he presses the push button PB (see Fig. 1A). Depression of this push button PB opens the circuit for the relay FR and also breaks the usual stepping circuit at the contact 90 of this push button PB, and movement of the contact at to its lower position connects the terminal (3+) of the battery 92 to the stepping line 9i, thereby operating all the line relays LR, LR and LR to their right hand position. Movement of the contacts of relays LR and LE to their right hand position, completes the following pick-up circuit for the announcer relays AR and AR :-beginning at the terminal of the waiy station battery (see Fig. 2), contact I02 of the line relay LE to the right, wires I03 and 550, back contact 55l of the relay 1 wires 552 and 553, winding of the relay AR and to the other terminal of the way station battery. The circuit for the relay AR. has been traced by the same reference characters with distinctive exponents 3.

The relay AB is then stuck up through a stick circuit readily traced in the drawings and including a stick contact 554 of this same relay, as is also true of the relay AR The various slow acting relays I, I and I will of course pick up after a short interval of time, but in spite of this the announcer relays AR and AR remain in their attracted position. The transmitter 545 (see Fig. 1A) is now connected to the various receivers 545 and 546 in multiple, through the following circuit:-beginning at the terminal (13+) of the battery 92, transmitter 545, wire 5%, contact 55'! of the push button PB, wires 558 and. E25, front contact I28 of the relay I, message wire ifiil, wire 39'! (see Fig. 2), front contact I29 of the relay 1 wire 398, contacts 399, 3M, 404, M6, M3, M2, MI and 440 of the relays 8 i 6 5 4 3 2 and 1 respectively, wire 559, front contact 569 of the relay AR wire 53L the receiver 546 and to the common return wire C connected to the mid-point of the battery 92, the receivers in the other way stations being connected in multiple with the receiver. 556 by identical circuits, readily traced see, for instance Fig. 3 of the drawings.

The operator may thus speak or telegraph by telephone or telegraph printers to each of the various station agents simultaneously, and may thereby inform them in a convenient manner the conditions of train performance. The operator, so long as he is communicating with these various station agents, maintains the push button PB depressed, and as soon as this push button PB is released, the field starting relay FR is again conditioned so that any change of indications which have materialized and accumulated in the meantime may initiate the system and cause it to indicate such change in the central office equipment.

Attention is particularly directed to the fact that the system under consideration requires no lock-out between the various way stations, in spite of the fact that a plurality of these way stations may dictate a code to get in communication with the central ofiice simultaneously. The reason that no lock-out is required resides in the fact that each code is either superior or inferior to every other code, so that there is only one code of the codes of a plurality of way stations which want to connect with the central office at a particular time, which dominates the codes of all the other way stations. Another reason for not requiring an interlock, is that the slow acting or cycle demarking relays such as I and I require the various way stations to take their first step simultaneously, since after a particular slow acting relay is once energized the first relay of the particular code responsive relay group can not be picked up. Attention is also directed to the fact that if desired the relay groups employed in the central office may be constructed like the relay group illustrated in Fig. 3 of the drawings, that is, may use the even and odd relays instead of employing the half-step relay s as shown in Fig. 2 of the drawings and as em ployed in the relay groups illustrated in Fig. 1B of the drawings.

Applicant has thus provided a rather unique system of centralized trafiic control, which employs only three line wires leading to a large number of distributed way stations, through the medium of which he may control apparatus at such way stations and receive indications from such way stations in such rapid sequence that all of the control functions and indications which may be required on a railway system extending for a distance as of as much as a hundred miles, or even more. In this system codes of impulses are employed in which the number of distinctive codes available is equal to two to the nth power where n represents the number of steps per cycle, that is 4 steps afford 2 codes, namely 16, 5 steps afford 2 or 32 codes, and so on. The system is such that the central ofiice equipment determines the code when a distant way station is to be controlled from the central office equipment, the system being so organized, however, that when a way station wants to transmit an indication to the central ofiice, the way station will initiate the central ofiiice equipment and will then dictate the code step by step, the apparatus being so constructed that if two or more way stations endeavor to dictate the code step by step, the way station having the largest number of dominating steps in prior order will be able to dictate the selection of its own code by the central oilice. Each way station, as above described, has a series of stepping relays which will be energized successively providing the code impressed on the stepping circuit is proper, this series of stepping relays discontinuing their stepping as soon as a particular step in the code is of the wrong polarity, the advantage of this characteristic resides in the fact that if the portion of the code which has already been transmitted is wrong for a particular way station, this way station drops out, so to speak, and is thereafter unable to dictate the nature of the code to be transmitted by the central ofiice equipment. The system under consideration retains the advantage of having multiple message circuits connecting the central oflice and a large number of way stations, these message circuits ordinarily being completed sequentially, but if desired may be completed simultaneously to enable simultaneous communication, such as the operation of a plurality of printing telegraphs or loud speakers, at all of the way stations, these message circuits also permitting the reading of battery voltages at different way stations sequentially, if desired. The proposed system is exceedingly simple in that no lock-out is required between the various way stations, the system being so organized that where a plurality of way stations desire to communicate with the central ofiice at the same time, these way stations will have their code cycles synchronized, so to speak, in that they will all take their steps synchronously, this being accomplished by a channel defining or demarking relay which requires that all Way stations take their first step, and successive steps, synchronously. Also, the system is very fast in its operation in that a comparatively few steps in a particular cycle enable one of a very large number of way stations to be selected. Other advantages and characteristic features are understood from the drawings and the preceding description.

Having thus shown and described two rather specific embodiments of the present invention it is desired to be understood that the particular embodiments illustrated have been selected for i the purpose of conveniently describing the underlying principles of the invention, as Well as its operating characteristics and the advantages afforded thereby, and that the particular forms of the invention illustrated have not been selected as the exact construction preferably employed in practicing the invention .and should not be interpreted as a limitation of the invention and it is further desired to be understood that various changes and modifications may be made to adapt the invention to the particular problem encountered in practicing the same, all without departing from the spirit or scope of the invention or the idea of means underlying the same, except as demanded by the scope of the following claims.

What I claim as new is:

1. In a centralized trafiic controlling system for railroads, the combination with a stepping circuit and a message circuit connecting a central ofiice and a plurality of way stations, coding means in the central office for impressing a code of impulses upon the stepping circuit to select a particular Way station irrespective of whether such way station is to be controlled from said central office or whether an indication is to be transmitted from such way station to said central ofiice, means in the central office having its operation manually initiated for determining the character of the code impressed by said coding means at times when a Way station is to be controlled from said central oflice, and means at each way station operable at other times for dictating through the medium of said message circuit the character of the code to be impressed by said coding means when such way station is in condition to transmit a new indication to the central oflice.

2. In a centralized traffic controlling system for railroads, the combination with a stepping circuit and a message circuit connecting a central ofliceand a plurality of way stations, coding means in the central o-fiice for impressing a code of impulses upon the stepping circuit to select a particular way station irrespective of whether controls are to be transmitted to such way station from said central ofiice or whether an indication is to be transmitted from such way station to said central oflice, control means in the central office for determining the character of the code impressed by said coding means when a way'station is to be controlled from said central office, means at each way station and operable only if said control means is not eflective for dictating through the medium of said message circuit the character of the code to be impressed by said coding means to select such way station When such way station is in condition to transmit a new indication to the central office, and means for transmitting an indication through the medium of said message circuit when such Way station has been selected.

3. In a centralized trafiic controlling system for railroads, the combination with a stepping line circuit and a message line circuit connecting a central office and a Way station, a series of relays in said central office operated successively step by step in response to a particular code impressed upon said stepping circuit, means associated with said series of relays for in response to one step in said code dictating the character of and impressing the code impulse for the next step on said stepping line circuit, and means at said station rendered available by said particular code on said stepping line circuit for indicating in said central office and over said message circuit the condition of trafiic at that particular distant way station.

4. In a centralized traffic controlling system for railroads, the combination with a line circuit connecting a central ofiice and a plurality of way 

